ch.qos.logback.core.pattern.parser.Parser Maven / Gradle / Ivy

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With inspiration from other libraries
There is a newer version: 2.12.15
/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.core.pattern.parser;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import ch.qos.logback.core.CoreConstants;
import ch.qos.logback.core.pattern.Converter;
import ch.qos.logback.core.pattern.FormatInfo;
import ch.qos.logback.core.pattern.IdentityCompositeConverter;
import ch.qos.logback.core.pattern.ReplacingCompositeConverter;
import ch.qos.logback.core.pattern.util.IEscapeUtil;
import ch.qos.logback.core.pattern.util.RegularEscapeUtil;
import ch.qos.logback.core.spi.ContextAwareBase;
import ch.qos.logback.core.spi.ScanException;

// ~=lamda
// E = TE|T

// Left factorization
// E = T(E|~)
// Eopt = E|~
// replace E|~ with Eopt in E
// E = TEopt

// T = LITERAL | '%' C | '%' FORMAT_MODIFIER C
// C = SIMPLE_KEYWORD OPTION | COMPOSITE_KEYWORD COMPOSITE
// OPTION = {...} | ~
// COMPOSITE = E ')' OPTION

public class Parser extends ContextAwareBase {

    public final static String MISSING_RIGHT_PARENTHESIS = CoreConstants.CODES_URL + "#missingRightParenthesis";
    public final static Map DEFAULT_COMPOSITE_CONVERTER_MAP = new HashMap();
    public final static String REPLACE_CONVERTER_WORD = "replace";
    static {
        DEFAULT_COMPOSITE_CONVERTER_MAP.put(Token.BARE_COMPOSITE_KEYWORD_TOKEN.getValue().toString(), IdentityCompositeConverter.class.getName());
        DEFAULT_COMPOSITE_CONVERTER_MAP.put(REPLACE_CONVERTER_WORD, ReplacingCompositeConverter.class.getName());
    }

    final List tokenList;
    int pointer = 0;

    Parser(TokenStream ts) throws ScanException {
        this.tokenList = ts.tokenize();
    }

    public Parser(String pattern) throws ScanException {
        this(pattern, new RegularEscapeUtil());
    }

    public Parser(String pattern, IEscapeUtil escapeUtil) throws ScanException {
        try {
            TokenStream ts = new TokenStream(pattern, escapeUtil);
            this.tokenList = ts.tokenize();
        } catch (IllegalArgumentException npe) {
            throw new ScanException("Failed to initialize Parser", npe);
        }
    }

    /**
     * When the parsing step is done, the Node list can be transformed into a
     * converter chain.
     *
     * @param top
     * @param converterMap
     * @return
     * @throws ScanException
     */
    public Converter compile(final Node top, Map converterMap) {
        Compiler compiler = new Compiler(top, converterMap);
        compiler.setContext(context);
        // compiler.setStatusManager(statusManager);
        return compiler.compile();
    }

    public Node parse() throws ScanException {
        return E();
    }

    // E = TEopt
    Node E() throws ScanException {
        Node t = T();
        if (t == null) {
            return null;
        }
        Node eOpt = Eopt();
        if (eOpt != null) {
            t.setNext(eOpt);
        }
        return t;
    }

    // Eopt = E|~
    Node Eopt() throws ScanException {
        // System.out.println("in Eopt()");
        Token next = getCurentToken();
        // System.out.println("Current token is " + next);
        if (next == null) {
            return null;
        } else {
            return E();
        }
    }

    // T = LITERAL | '%' C | '%' FORMAT_MODIFIER C
    Node T() throws ScanException {
        Token t = getCurentToken();
        expectNotNull(t, "a LITERAL or '%'");

        switch (t.getType()) {
        case Token.LITERAL:
            advanceTokenPointer();
            return new Node(Node.LITERAL, t.getValue());
        case Token.PERCENT:
            advanceTokenPointer();
            // System.out.println("% token found");
            FormatInfo fi;
            Token u = getCurentToken();
            FormattingNode c;
            expectNotNull(u, "a FORMAT_MODIFIER, SIMPLE_KEYWORD or COMPOUND_KEYWORD");
            if (u.getType() == Token.FORMAT_MODIFIER) {
                fi = FormatInfo.valueOf((String) u.getValue());
                advanceTokenPointer();
                c = C();
                c.setFormatInfo(fi);
            } else {
                c = C();
            }
            return c;

        default:
            return null;

        }

    }

    FormattingNode C() throws ScanException {
        Token t = getCurentToken();
        // System.out.println("in C()");
        // System.out.println("Current token is " + t);
        expectNotNull(t, "a LEFT_PARENTHESIS or KEYWORD");
        int type = t.getType();
        switch (type) {
        case Token.SIMPLE_KEYWORD:
            return SINGLE();
        case Token.COMPOSITE_KEYWORD:
            advanceTokenPointer();
            return COMPOSITE(t.getValue().toString());
        default:
            throw new IllegalStateException("Unexpected token " + t);
        }
    }

    FormattingNode SINGLE() throws ScanException {
        // System.out.println("in SINGLE()");
        Token t = getNextToken();
        // System.out.println("==" + t);
        SimpleKeywordNode keywordNode = new SimpleKeywordNode(t.getValue());

        Token ot = getCurentToken();
        if (ot != null && ot.getType() == Token.OPTION) {
            List optionList = (List) ot.getValue();
            keywordNode.setOptions(optionList);
            advanceTokenPointer();
        }
        return keywordNode;
    }

    FormattingNode COMPOSITE(String keyword) throws ScanException {
        CompositeNode compositeNode = new CompositeNode(keyword);

        Node childNode = E();
        compositeNode.setChildNode(childNode);

        Token t = getNextToken();

        if (t == null || t.getType() != Token.RIGHT_PARENTHESIS) {
            String msg = "Expecting RIGHT_PARENTHESIS token but got " + t;
            addError(msg);
            addError("See also " + MISSING_RIGHT_PARENTHESIS);
            throw new ScanException(msg);
        }
        Token ot = getCurentToken();
        if (ot != null && ot.getType() == Token.OPTION) {
            List optionList = (List) ot.getValue();
            compositeNode.setOptions(optionList);
            advanceTokenPointer();
        }
        return compositeNode;
    }

    Token getNextToken() {
        if (pointer < tokenList.size()) {
            return (Token) tokenList.get(pointer++);
        }
        return null;
    }

    Token getCurentToken() {
        if (pointer < tokenList.size()) {
            return (Token) tokenList.get(pointer);
        }
        return null;
    }

    void advanceTokenPointer() {
        pointer++;
    }

    void expectNotNull(Token t, String expected) {
        if (t == null) {
            throw new IllegalStateException("All tokens consumed but was expecting " + expected);
        }
    }

    // public void setStatusManager(StatusManager statusManager) {
    // this.statusManager = statusManager;
    // }
}